The Annals of thoracic surgery
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Profound hypothermic circulatory arrest and profound hypothermia with continuous low-flow cardiopulmonary bypass are used to facilitate repair of complex congenital heart lesions. Extended periods of profound hypothermic arrest may impair cerebral function and metabolism and produce ischemic brain injury. Low-flow bypass has been advocated as preferable to profound hypothermic arrest with respect to neurologic outcome as it maintains continuous cerebral circulation during repair of heart defects. ⋯ Transcranial Doppler sonography has enabled the noninvasive study of cerebral perfusion during operations using either circulatory arrest or low-flow bypass. Although these studies have demonstrated the presence of cerebral perfusion at low perfusion pressures, evidence exists to suggest that cerebral perfusion abruptly ceases at cerebral perfusion pressures of 7 to 9 mm Hg and is unrelated to pump flow rate. Transcranial Doppler sonography is a useful tool for monitoring cerebral perfusion during low-flow bypass, and future studies with this modality may help to develop improved modes of cerebral protection during repair of complex congenital heart lesions.
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Cerebral complications constitute the leading source of morbidity and disability after cardiac operations. The incidence of stroke after coronary artery bypass grafting has increased in tandem with the mean age of the patient population. Although many cerebral deficits resolve with time, others remain sources of disability for otherwise functional patients and detract from an otherwise successful procedure. ⋯ Potential mechanisms include macroembolization of air or particulate matter; microembolization of gas, fat, aggregates of blood cells, platelets or fibrin, and particles of silicone or polyvinylchloride tubing; and inadequate cerebral perfusion pressure. Methods of assessment include those applied during the procedure (clinical observation, assessment of cerebral blood flow and metabolism, intraoperative electroencephalography, transcranial and carotid Doppler echography, quantitative embolic measurement, and fluorescein angiography) and those performed to measure outcome (neurologic and neuropsychologic testing, computed tomographic scans, magnetic resonance imaging, and cerebrospinal fluid studies). Much of the literature regarding cerebral injury and cardiopulmonary bypass is descriptive, relating patient risk factors to the incidence of postoperative stroke.(ABSTRACT TRUNCATED AT 250 WORDS)
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Thoracic surgeons have recently pursued innovative techniques that can help minimize postoperative pain. These have taken two basic directions. The first consists of a modification of the operative procedure itself, such that the surgical insult and hence the resulting pain are minimized. ⋯ Many authors have advocated the induction of spinal analgesia after thoracotomy, using either epidural opioids or local anesthesia, or both. Patient-controlled analgesia and multiple intercostal nerve blocks are other methods for managing postthoracotomy pain. The potential benefits conferred by aggressive pain control after thoracotomy are enormous for the patients, the surgeons, and the entire health-care system.
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Review
The role of the gut in the development of multiple organ dysfunction in cardiothoracic patients.
Interest in the importance of the gut after injury or operation has waxed and waned over this century. Recent studies implicate the gut in septic complications and multiple organ failure after trauma, operations including cardiothoracic procedures, starvation, and other serious illnesses. Changes in the gut in sick patients include stress ulceration, bacterial overgrowth from stress ulceration prophylaxis, mucosal atrophy, loss of barrier function, increased permeability, and bacterial translocation. ⋯ Louis University Hospital from 1985 to 1991, multiorgan failure developed in 128 patients, with a mortality of 78%. Significant gastrointestinal problems occurred and contributed to multiorgan failure in a number of these patients. Support of the gastrointestinal tract and the prevention of multiorgan failure are important for the cardiothoracic surgeon.
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Cardiac operations with cardiopulmonary bypass cause a systemic inflammatory response, which can lead to organ injury and postoperative morbidity. Causative factors include surgical trauma, contact of blood with the extracorporeal circuit, and lung reperfusion injury on discontinuing bypass. ⋯ This includes activation of the complement, coagulation, fibrinolytic, and kallikrein cascades, activation of neutrophils with degranulation and protease enzyme release, oxygen radical production, and the synthesis of various cytokines from mononuclear cells (including tumor necrosis factor, interleukin-1, and interleukin-6). Advances in our understanding of the interactions between these markers of cellular and humoral responses to cardiopulmonary bypass will enable more effective intervention to reduce the deleterious effects and improve the outlook for patients undergoing cardiac operations beyond the 1990s.